U.S. patent number 5,419,688 [Application Number 08/267,416] was granted by the patent office on 1995-05-30 for mounting for oilless air compressor.
This patent grant is currently assigned to Carrier Corporation. Invention is credited to Edward M. Basinski, John H. Bolthouse, II, Richard L. Martin, M. Wayne Meece.
United States Patent |
5,419,688 |
Basinski , et al. |
May 30, 1995 |
**Please see images for:
( Certificate of Correction ) ** |
Mounting for oilless air compressor
Abstract
An oilless reciprocating air compressor that is mountable on the
inside wall of a cargo container. The compressor has a high
strength cast metal crank case and a lighter motor housing attached
thereto. A special bracket is provided that attaches to both the
crank case and the motor housing to support the motor shaft in a
horizontal plane and the opposed cylinders of the compressor in a
vertical plane adjacent to the wall. Because this compressor
mounted inside the container cooling fans and the like are not
required, thus lightening the compressor and allowing for a compact
unit that can be safely secured to the cargo container wall.
Inventors: |
Basinski; Edward M. (Manlius,
NY), Martin; Richard L. (Cicero, NY), Meece; M. Wayne
(Monroe, LA), Bolthouse, II; John H. (Monroe, LA) |
Assignee: |
Carrier Corporation (Syracuse,
NY)
|
Family
ID: |
23018679 |
Appl.
No.: |
08/267,416 |
Filed: |
June 28, 1994 |
Current U.S.
Class: |
417/423.15;
92/147; 92/150; 92/161 |
Current CPC
Class: |
F04B
39/00 (20130101); F04B 41/02 (20130101) |
Current International
Class: |
F04B
39/00 (20060101); F04B 41/00 (20060101); F04B
41/02 (20060101); F04B 017/00 () |
Field of
Search: |
;62/295,297,78
;92/146,147,150,161,153,154 ;417/360,423.15,361 ;99/473,474,475,476
;248/309.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Denion; Thomas E.
Claims
What is claimed is:
1. An oilless reciprocating air compressor for use inside an air
conditioned cargo container that includes
a motor housing containing a stator and a shaft mounted rotor, said
shaft being rotatably supported upon sealed bearings,
a high strength crank case secured to one end of said motor housing
with one end of said shaft extending into said crank case,
at least one cylinder mounted upon the crank case, and containing
piston means connected to the shaft by rod means,
a plate mounted on said motor housing, said plate being parallel to
the axis of said cylinder,
a bracket means having a base leg secured to said plate and an arm
secured to said crank case, and
fastening means for securing the base leg of said bracket means to
a vertical inside wall of the cargo container with the shaft being
horizontally disposed and the cylinder being vertically disposed
adjacent said wall.
2. The compressor according to claim 1, wherein said cylinder
comprises a pair of opposed cylinders, said cylinders being
coaligned along a common axis.
3. The compressor according to claim 1, wherein said cylinder
comprises a plurality of cylinders.
4. The air compressed of claim 1 wherein said crank case includes a
bolting flange and the arm of said bracket means is attached to the
bolting flange by threaded means.
5. The air compressor of claim 1 that further includes a bypass
line for placing the crank case in fluid flow communication with
the cylinder.
6. The air compressor of claim 1 wherein the external surfaces of
the cylinder include cooling fins whereby the cylinder is cooled by
conditioned air contained inside said cargo container.
7. The air compressor of claim 1 wherein said motor housing is
cylindrically shaped and said plate is mounted in tangential
contact against the motor housing.
8. The air compressor of claim 1 wherein the crank case has greater
load carrying capacity than the motor housing.
9. The air compressor of claim 6 wherein both the crank case and
the motor housing are formed of metal.
10. The air compressor of claim 1 wherein said compressor further
includes a discharge line for exhausting high pressure air from
said cylinder and membrane means for extracting nitrogen gas from
the high pressure air and delivering said nitrogen gas into said
cargo container.
11. A method for using an oilless reciprocating air compressor
inside an air conditioned cargo container, the compressor being of
the type that includes:
a motor housing containing a stator and a shaft mounted rotor, said
shaft being rotatably supported upon sealed bearings;
a high strength crank case secured to one end of said motor housing
with one end of said shaft extending into said crank case; and
a pair of opposed cylinders mounted upon the crank case, said
cylinders being coaligned along a common axis and containing piston
means connected to the shaft by rod means;
the method comprising the steps of:
mounting a plate on said motor housing, said plate being parallel
to the axis of said cylinders;
securing said plate to an arm portion of a bracket, and securing a
base leg portion of said bracket to the crank case of the motor
housing, to securely hold the motor housing in said bracket;
and
securing the bracket to a vertical inside wall of the cargo
container with the shaft being horizontally disposed and the
cylinders being vertically disposed adjacent said wall.
Description
BACKGROUND OF THE INVENTION
This invention relates to an oilless reciprocal compressor that is
suitable for mounting on the inside wall of a cargo container and
for carrying perishable foodstuffs such as fruits and
vegetables.
Cargo containers are typically carried on the open decks of sea
going vessels and are thus exposed to a harsh salt air environment.
The containers are made generally air tight and the inside
environment of the container is maintained at a desired temperature
by self-sustaining air conditioning equipment. As many of the
components as possible are brought inside the container to protect
them from the harsh outside environment. This however, consumes
valuable cargo space and it is therefore important to package the
equipment to minimize space.
The cargo containers typically undergo rough handling, oftentimes
being bumped or dropped from relatively high elevations as they are
being loaded and unloaded from carriers. Accordingly, the equipment
stored in the container must be securely fastened in place so that
it cannot break loose thus endangering the cargo.
In the case of cargo containers used to carry perishable fruits and
vegetables, it is highly desirable to replace the oxygen within the
container with nitrogen gas which serves to better preserve the
perishable foodstuff. To this end, systems have been derived
wherein outside air is first compressed and then passes through a
series of filters and membranes to separate nitrogen gas from the
incoming air. The nitrogen is discharged into the container while
the other separated air constituents, including oxygen, are
exhausted to ambient.
Small reciprocating air compressors such as the compressor
described in U.S. Pat. No. 5,244,363 to Olson possess the operating
parameters that are required for use in this type of nitrogen
generation system. The prior art compressors, however, have two
undesirable features that make them less than attractive for use in
this particular application. First, crankcase oil can move past the
piston rings and find its way into the compressed air stream. This,
in turn, has an adverse effect on downstream filters and separating
membranes as well as the products stored in the container.
Secondly, reciprocating air compressors that are presently
available generally include self contained cooling fans that are
space consuming. They also have relatively weak mounting brackets
that cannot withstand the rough handling that a cargo container is
exposed to and do not lend themselves to wall mounting because of
bearing loading considerations.
SUMMARY OF THE INVENTION
It is therefore an object to improve reciprocating air compressors
for use in cargo containers.
It is a further object of the present invention to adapt
reciprocating air compressor for use in a cargo container.
A still further object of the present invention is to provide a
wall mounting arrangement for a reciprocating air compressor so
that the compressor can be effectively utilized in a cargo
container.
Another object of the present invention is to securely mount a
reciprocating air compressor on a vertical side wall of a cargo
container in a space saving configuration to avoid thrust loading
of the shaft bearing.
These and other objects of the present invention are attained by an
oilless reciprocating air compressor having a high strength crank
case attached to a lesser strength motor housing. Opposed
compression cylinders are mounted on the crank case which contain
pistons attached to the motor shaft. The motor housing further
contains a mounting plate that is fastened to a bracket for
supporting the compressor upon a vertical wall of a cargo
container. The bracket is also secured to the crank case to provide
an extremely strong and secure mounting arrangement. The bracket is
configured so that the compressor can be attached to an inside
vertical wall of the container with the motor shaft being
horizontally disposed and the opposed cylinders being vertically
disposed adjacent to the wall. Because the compressor is exposed to
the air conditioned atmosphere inside the container it does not
require its own cooling fan. This, coupled with the wall mounting
arrangement, allows for a compact space saving configuration that
is really suited for use in a cargo container.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of these and other objects of the
present invention reference will be made to the following detailed
description of the invention which is to be read in association
with the accompanying drawings wherein:
FIG. 1 is a end view of a cargo container with portions broken away
showing a reciprocating air compressor mounted on the front
vertical wall of the container;
FIG. 2 is a top view of the cargo container illustrated in FIG. 1
with a portion broken away showing the air compressor mounted
within the equipment compartment of the cargo container; and
FIG. 3 is an enlarged side elevation showing a reciprocal air
compressor embodying the teachings of the present invention.
DESCRIPTION OF THE INVENTION
Turning now to the drawings and in particular to FIGS. 1 and 2,
there is shown a cargo container generally referenced 10 of the
type typically used to store perishable foods such as fruits,
vegetables and the like. This type of container is generally moved
by ship, rails or track over relatively long distances and as a
consequence has its own independently operated air conditioning
system (not shown) for controlling the climate inside the
container. The climate support equipment is usually stored in a bay
or compartment 12, (FIG. 2) located along the front wall 13 of the
container. As noted above, this equipment consumes valuable
container space and it is therefore important to minimize the
amount of space that is needed by the equipment.
In this type of container it is the usual practice to replace the
oxygen inside the container with nitrogen gas to help preserve the
cargo during long trips. This is accomplished by an air handling
system that includes an air compressor for raising the pressure of
ambient or outside air. High pressure air discharged from the
compressor is passed through a condenser and a series of filters to
remove water and particulate material from the air stream. The
clean air is then passed through a separator having a series of
membranes for separating nitrogen gas from oxygen and other
unwanted constituents. The oxygen and other lesser separated
components are passed on to the atmosphere outside the container
while the nitrogen is added to the atmosphere inside the
container.
As in the case of the other air conditioning and climate control
equipment, it is highly desirous to compact the nitrogen generating
equipment as much as possible without sacrificing performance. The
major space consuming component in the nitrogen generating system
is the air compressor. As will be explained in greater detail
below, the apparatus of the present invention involves a reciprocal
air compressor that can be securely mounted on a vertical wall in
the equipment compartment of a cargo container which utilizes a
minimum amount of space without adversely effecting compressor
performance.
As illustrated in FIGS. 1 and 2, the compressor 14 is hung high on
the front wall 13 of the container and includes a motor housing 15,
a crank case 16 and a pair of opposed piston cylinders 17 and 18
connected to the crank case. While two opposed cylinders are used
in the preferred embodiment, the invention can be practiced with
any number of cylinders. An electric motor is contained within the
motor housing which includes a stator 20 and a rotor 21. The rotor
is mounted upon a shaft 23 which in turn is supported by sealed
bearings 25 and 26. The shaft is arranged to extend into the crank
case and is connected to pistons that are slidably contained in the
opposed cylinders by means of suitable piston rods (not shown).
Outside air is drawn into the cylinders where it is compressed and
then discharged from the compressor in the manner described in the
previously noted patent to Olson.
As further illustrated in FIG. 3, the motor housing 15 includes a
relatively thin walled cylindrical metal shell 27 that is joined at
one end to the crank case 16. The crank case consists of two cast
metal half sections 28 and 29 that are brought together by means of
a bolting flange 30. The two half sections secured in assembly by
means of bolts 32--32 and nuts 33--33 that are threaded
thereon.
Suitable seals are contained within the compressor unit to prevent
the working fluid from escaping from the compressor. The pistons
contained within the cylinders also have sliding rings which to a
large extent prevent air from being exchanged between the cylinders
and the crank case. Any process air that might blow by the piston
rings is conveyed back to the cylinders by means of a blowby line
35 and thus can not find its way into the container where it might
adversely effect the nitrogen content in the container. The air
compressed within the cylinders is delivered via line 39 into an
air manifold 40 from which it is passed via discharge line 41 to a
nitrogen separator 42. Although not shown, suitable condensing
lines and particle filter may be operatively connected into the
discharge line.
In the separator 42 oxygen and other lesser components are
separated from the nitrogen gas. The oxygen and other unwanted
components are exhausted to the surrounding ambient by line 44 and
the nitrogen gas is delivered into the container via supply line
45.
The two opposed cylinders of the compressor are aligned along a
common axis 50. It is important when mounting a reciprocal
compressor of this type that the shaft of the motor be aligned in a
horizontal plane. When the compressor is mounted in this position,
the shaft bearings will be placed almost entirely under a radial
load which they are well able to accept. Tilting the centerline of
the motor shaft away from the horizontal plane will produce a
thrust loading in the bearings which they are not well able to
resist, thereby leading to early compressor failure. As can be
seen, due to bearing considerations, care must be taken to properly
mount the compressor on the vertical wall of a cargo container.
The motor housing of the compressor is formed of a cylindrical
sheet metal tube 60 closed at the distal end by means of an end cap
61. A flat plate 63 is typically spot welded to the housing so that
the plate is situated in a plane that is parallel to the axis 50 of
the cylinders. The plate 63 is provided with a series of slotted
holes 65--65.
In assembly, the plate is positioned in tangential contact against
the surface of the motor housing. As noted above, the proximal end
of the housing is secured and sealed in the crank case 16. The two
half sections of the crank case are cast from a suitable metal and
are bolted together in assembly along the bolting flange 30. The
cast metal crank case, which is relatively stronger than the motor
housing, in a sense forms the structural hub or backbone of the
compressor. The crank case is manufactured of cast aluminum, which
is thicker than the sheet metal of the motor housing. In the
preferred embodiment the motor housing is 90 mil steel sheet metal,
and the crank case has a cast aluminum shell that is about 400 mil
thick. As will be seen from the disclosure below, the strength of
the crank case is used as the basis for securely affixing the
compressor to the vertical inner wall of the cargo container so
that the mounted compressor is well able to withstand the stress
induced therein due to rough handling as the container is loaded
and unloaded from a carrier.
An L-shaped bracket 70 is used to affix the compressor to the
vertical front wall of the container. The bracket includes a flat
base 71 and an upwardly turned arm 73. The base has a series of
slotted holes 75--75 that align with holes formed in plate 63. The
base and the plate are placed in face to face relationship in
assembly and threaded fasteners 75 are passed through the aligned
holes to secure the compressor to the inner wall of the cargo
container. In addition, arm 73 of the bracket has a pair of holes
78--78 that are adapted to fall in alignment with the bolt holes in
the bolting flange 30 on the crank case. Bolts 32--32 are arranged
to pass through the flange and the holes in the bracket arm and the
bracket is secured to the flange and thus the crank case by
threading nuts 33--33 onto the bolts.
As can be seen the mounting bracket is thus secured to both the
motor housing and the stronger crank case structure. According, an
extremely secure mounting for the compressor is achieved when the
bracket is affixed to the container wall. Enough tolerance is
provided in the elongated mounting holes of the bracket to allow
the compressor shaft to be accurately aligned in a horizontal plane
on the wall. Because the motor housing plate 63 is in tangential
contact against the motor housing the cylinders of the housing can
be placed in close proximity to and adjacent with the wall surface.
In light of the fact that the compressor is exposed to the climatic
conditions within the cargo containers, the compressor does not
require additional cooling and therefore bulky space consuming fans
can be eliminated from the compressor design. The net result is a
compact low profile compressor that can be securely mounted upon
the vertical wall of a cargo container in a position that minimizes
thrust loading of the compressor shaft bearings.
While this invention has been described in detail with reference to
a certain preferred embodiment, it should be appreciated that the
present invention is not limited to that precise embodiment.
Rather, in view of the present disclosure which describes the best
mode for practicing the invention, many modifications and
variations would present themselves to those of skill in the art
without departing from the scope and spirit of this invention, as
defined in the following claims.
* * * * *